1. Field of the Invention
The present invention relates to a surgical device for bone anchoring, and more particularly to a surgical device permitting simple and effective anchoring of suture thread or surgical thread on a bone support, in particular in orthopedic surgery, trauma surgery, gynecological surgery and cancer surgery.
2. Description of the Related Art
Tearing of tendons or of ligaments is something which can happen to many individuals of all ages, whether active or inactive, following traumas or excessive strains. The reparative surgical techniques currently used consist in attaching the tendon, by means of a suture thread, to a screw, a peg or a piton fixed in the adjoining bone.
To do this, the conventional technique consists in boring, in the bone, either a tapped hole, so that a screw or piton can be screwed into it, or an untapped hole receiving a peg which can be locked in the bone. The screw, the piton or the peg serves as an anchoring means on which one then attaches a suture thread which is used to re-attach the tendon which has been torn from its bone support. In other techniques, after a hole has been bored which is able to receive an anchoring piton, the suture thread is passed through the eye of the anchoring piton, then the latter is introduced into the hole by means of a special instrument, and finally the tendon to be fixed is sutured. An example of an anchoring screw for fixing tissues by means of a suture thread is described in the patent U.S. Pat. No. 5,443,482.
Depending on the circumstances, the operations can be performed by open surgery or by closed surgery using celioscopy or arthroscopy procedures. Surgical techniques using devices of this type are described, for example, by F. A. Barber et al., J. of Arthroscopy and Related Surgery, vol. 11, No. 1, pages 21 to 28 (1995).
The patent U.S. Pat. No. 5,403,348 describes a bone-anchoring device comprising a rigid cylindrical component with a surgical thread passing along its axis, which is introduced into a hole bored in the bone, as far as the spongy substance. By acting on the thread, the orientation of the cylindrical component is modified in such a way as to block it under the solid superficial layer of the cortical bone, deforming the spongy substance.
The patent EP-A-611,551 describes an anchoring device for a suture thread, including a rivet intended to be fixed in the bone support, formed by two elements: a spike, and a rigid sleeve in which it can slide. Another anchoring device is described in the patent U.S. Pat. No. 5,584,695, comprising a rivet with shape memory, capable of being introduced in the cold state into the bone support and of expanding in the hot state so as to cause blocking.
These known devices have various disadvantages. They are highly invasive and are non-absorbable, and their positioning involves techniques which are often awkward to perform. Moreover, some of the known devices include items containing allergenic materials, for example certain shape-memory materials, and according to some authors these materials are sometimes carcinogenic. In addition, a large number of screws, pegs or pitons, of accessories for boring into the bone and of accessories for positioning the anchoring means must be available in various sizes so as to be able to respond to all situations.
The subject of the present invention is a bone-anchoring device which necessitates only the prior boring of a single hole with any wall shape, without requiring tapping, and permitting fixation of organs such as tendons and ligaments, or suspension of the cervix of the uterus, using a surgical thread or a suture thread without the need to use a means of the screw or piton type.
The invention also describes an ancillary instrument specially adapted for placing the aforementioned anchoring device in position.
The anchoring device according to the present invention can be used in combination with a hole bored in the bone support, and it comprises a deformable tubular sleeve, associated with means capable of deforming it between a first stretched position of small diameter and a second folded position of greater diameter.
The length of the tubular sleeve in the stretched position must be substantially greater than the diameter to ensure maximum efficacy of the device. More precisely, the length of the sleeve must be equal to at least 5 times the diameter, and preferably at least ten times the external diameter of the sleeve.
According to the invention, the means capable of deforming the sleeve are made up of a thread passing through the deformable tubular sleeve along its axis and forming a closed loop, the tubular sleeve being located on the thread, in the loop-shaped part. The internal diameter of the sleeve must be sufficient to contain the thread without causing too great a frictional force. By way of example, a tubular sleeve can be used having a length of between about 15 and 30 mm, an external diameter of between 1 and 2 mm, and an internal diameter of between 0.6 and 1.2 mm.
Thus, in its preferred embodiment, the boneanchoring device of the invention comprises a thread having a middle part intended to be introduced into the hole bored beforehand, having a closed loop shape, bearing on the loop-shaped part a deformable tubular envelope or sleeve which is able to slide on the thread within the limits of the loop. The closure of the loop can be obtained by simple crossing of the two strands of the thread, on either side of the deformable sleeve. The tubular sleeve can be deformed into a ball by simple traction exerted on at least one strand of the thread.
According to the present invention, the thread used is preferably a surgical thread or a suture thread, absorbable or non-absorbable, of the type used to fix or re-attach organs. For example, it is possible to use a polyester thread such as the one marketed under the brand name Ercylene(copyright), or a polyamide thread such as Trynil(copyright). Thus, the thread serves both for causing deformation of the tubular sleeve and also for fixation of the organs.
The tubular envelope or sleeve capable of sliding on the thread in the loop has a total length which is less than or equal to about twice the depth of drilling in the bone, and a diameter which is less than or equal to that of the hole bored in the bone. Thus, the loop bearing the sleeve is fully introduced into the hole bored in the bone. This sleeve can advantageously be made of any deformable material, preferably one which has a certain elasticity, which has the property of being implantable, and which is absorbable or non-absorbable (for example a braided metal or plastic wire, a tube made of polyester or polyamide, or a tube made of silicone).
Depending on the circumstances, the sleeve can be made up of a single element or of several elements.
At the time of positioning, after introduction of the sleeve and of the thread into the hole bored in the bone, when the loop is tightened by pulling on at least one of the two strands of the thread, the latter is applied against the sleeve and causes its deformation, changing it from a first stretched position to a second position in which it is folded on itself and in which its cross section is increased. More precisely, having folded the sleeve at its middle in such a way that the strands of the thread emerge in the same direction, and having introduced it thus into the hole bored in the bone, by exerting a traction on the strands of the thread in diverging directions, the sleeve is folded until it presents approximately the form of a ball which, because its diameter is greater than that of the sleeve, is compressed against the walls of the hole into which the sleeve has been introduced. By reason of this pressure, the device is then held firmly in the hole bored in the bone.
According to a simple embodiment, the sleeve in the form of a linear cylinder is slipped onto the thread, and the loop is then formed around the sleeve.
In another simple embodiment, the sleeve can be preformed in a U shape and the thread passes into the sleeve via one of its two open ends, emerges via the second end and forms a loop before passing again into the sleeve via the first end in order to exit via the second end. In one variant, the sleeve can include an orifice extending through its wall near each of the two ends, and the thread can pass into the sleeve, then emerge therefrom via one or other of its orifices. In this latter embodiment, if the orifices are arranged asymmetrically with respect to the center plane of the loop, the traction exerted on the strands of the thread in order to cause compression of the sleeve also results in a tilting effect which adds to and reinforces the friction and blocking against the inner walls of the hole bored in the bone.
These orifices are arranged symmetrically with respect to the middle of the deformable sleeve, near to the ends, or in its central part. It is preferable to provide two orifices arranged in the same diametrical plane of the sleeve.
According to another embodiment of the invention, the sleeve is in the form of a toric ring which has at least one orifice extending through its wall for the passage of the two strands of the thread. In this alternative embodiment, the thread passes into the sleeve via the orifice, forms a complete loop along the inside of the annular sleeve, and emerges via the same orifice.
The sleeve is preferably reinforced in the zone where the thread passes into it, that is to say on the periphery of each of its ends, or around the orifices made in its wall, as appropriate. This reinforcement can be obtained, for example, by providing an extra thickness of material or by adhesive bonding or welding of a strip having greater strength.
The tubular sleeve can be open at its two ends, or by contrast can be closed. In this case, it includes at least two orifices in its wall for the passage of the strands of the thread. The wall of the tubular sleeve is preferably traversed by at least two orifices for the passage of the strands of the thread, these orifices being arranged in such a way that the traction exerted on the strands of the thread causes a tilting movement of the sleeve, promoting its anchoring against the walls of the hole bored in the bone.
The ancillary instrument for positioning the anchoring device according to the present invention essentially comprises a rod capable of carrying the thread and its sleeve for introducing them into the hole bored in the bone, as well as a slotted cylindrical component enclosing the thread and the sleeve and capable of sliding on the rod along a distance corresponding to the depth of the hole.
According to a preferred embodiment, the sliding of the cylindrical component is guided by a rib formed on the rod and cooperating with the slot.
According to another characteristic of the present invention, the ancillary instrument comprises a handle which is integral with the rod and which has a grip part facilitating its manipulation.
The sliding cylindrical component is made of a material compatible with use in a surgical environment.
The ancillary instrument for positioning of the anchoring device of the invention is easily used by introducing the point of the rod of the ancillary instrument, bearing the loop-shaped thread and its sleeve, into the hole bored beforehand in the bone, until the loop is fully engaged in the hole. After withdrawing the point from the hole, while leaving the thread and sleeve therein, it then suffices to exert a traction on one strand of the thread, while slightly holding the other strand still in order to cause tightening of the loop inside the hole in the bone and deformation of the sleeve on the loop until it adopts the shape of a ball, the diameter of which is greater than that of the tubular sleeve before deformation. With the traction being continued until locking occurs, the deformed sleeve then finds itself compressed against the inner walls of the cavity.
The two strands of the thread can then be knotted, at the edge of the hole bored in the bone, in order to lock the device and prevent its loosening, then, if necessary, attach the tendon or organ using the strands of the thread. Moreover, when the sleeve is folded into a ball shape, as indicated above, the enlargement of its diameter compared to the initial diameter of the sleeve, and the pleated shape of its surface, increase the phenomenon of anchoring in the spongy substance of the bone, resulting in improved fastening of the device of the invention in the bone.
As has been indicated above, the device and the ancillary positioning instrument according to the present invention are most particularly intended for reparative surgery of ligaments and tendons. The invention can also be used in gynecology, for example for fixing the uterus to the sacrum by way of a ligament.
The device of the invention is also suitable for cancer surgery, and in this application a thread is used which can contain a radioactive substance such as iridium. The thread is placed in the tumor, preferably using a non-absorbable thread, and the latter can serve as a marker for secondary ablation of the tumor.
Tests conducted with the anchoring device according to the present invention, carried out under experimental conditions, have revealed excellent properties of fixation and resistance to traction, comparable to, or even better than, those of the best of the known devices of the prior art.
The tests were conducted on two series of devices made up of sleeves of non-absorbable polyester braid with heat-bonded ends, of length equal to 20 mm for the 1st series, and 30 mm for the 2nd series. The sleeves have an external diameter of 1.6 mm and an internal diameter of 1.0 mm. A polyester suture thread measuring 0.5 mm in diameter (USP 2) is slipped inside the sleeve. The ends of the thread are knotted in order to form a loop.
The sleeves bearing the thread are introduced into a series of holes measuring 2.3 mm in diameter and 19 mm (sleeves of 30 mm) or 11 mm (sleeves of 20 mm) in depth, bored in a fresh human humerus. The tests on resistance to pulling-out in the axis of the hole are carried out using an Adamel Lhomargy DY 34 universal traction machine equipped with a calibrated 1 kN cell. A cylindrical bar integral with the mobile crosspiece of the machine is passed into a loop closed at the other end of the sample. The speed of displacement of the crosspiece is 5 mm/min. The tests are carried out until the device is torn from the bone support or the thread breaks.
In all cases, the suture thread was seen to break without the sleeve being pulled out of the hole bored in the bone. The force of resistance to pullingout varies between 10.2 and 12 kg for the samples in the two series.